Iowa Counties by Population (2026)
2026 Pop.
50K
100K
150K
200K
250K
300K
350K
400K
450K
500K
Top 5 Most Populous Counties
519,581
233,667
175,678
161,225
131,591
| County | 2026 Pop. ↓ | Area (mi²) | Density (/mi²) | Change (2020) |
|---|---|---|---|---|
| Polk County | 519,581 | 572 | 908 | 5.39% |
| Linn County | 233,667 | 717 | 326 | 1.42% |
| Scott County | 175,678 | 458 | 384 | 0.62% |
| Johnson County | 161,225 | 613 | 263 | 5.33% |
| Black Hawk County | 131,591 | 566 | 232 | 0.42% |
| Dallas County | 122,102 | 588 | 208 | 21.47% |
| Woodbury County | 106,556 | 873 | 122 | 0.57% |
| Story County | 101,164 | 573 | 177 | 2.54% |
| Dubuque County | 99,729 | 608 | 164 | 0.42% |
| Pottawattamie County | 92,722 | 951 | 97 | -1.01% |
| Warren County | 58,166 | 570 | 102 | 10.59% |
| Clinton County | 46,005 | 695 | 66 | -0.92% |
| Cerro Gordo County | 42,397 | 568 | 75 | -1.44% |
| Muscatine County | 41,545 | 437 | 95 | -3.72% |
| Marshall County | 39,652 | 573 | 69 | -1.12% |
| Jasper County | 38,184 | 730 | 52 | 0.96% |
| Des Moines County | 38,004 | 416 | 91 | -2.18% |
| Webster County | 36,877 | 716 | 52 | -0.32% |
| Sioux County | 36,771 | 768 | 48 | 2.46% |
| Wapello County | 34,991 | 432 | 81 | -0.97% |
| Marion County | 34,429 | 554 | 62 | 3.02% |
| Lee County | 32,132 | 518 | 62 | -4.16% |
| Boone County | 26,871 | 570 | 47 | 0.62% |
| Benton County | 26,163 | 716 | 37 | 2.39% |
| Plymouth County | 25,710 | 863 | 30 | 0.05% |
| Bremer County | 25,229 | 435 | 58 | 0.86% |
| Washington County | 22,732 | 569 | 40 | 0.87% |
| Mahaska County | 21,848 | 571 | 38 | -1.37% |
| Jones County | 21,335 | 576 | 37 | 3.28% |
| Buchanan County | 21,055 | 571 | 37 | 2.17% |
| Buena Vista County | 20,243 | 575 | 35 | -2.68% |
| Carroll County | 20,160 | 569 | 35 | -2.73% |
| Winneshiek County | 19,793 | 690 | 29 | -1.26% |
| Henry County | 19,330 | 434 | 45 | -5.48% |
| Jackson County | 19,225 | 636 | 30 | -1.14% |
| Fayette County | 18,984 | 731 | 26 | -2.39% |
| Cedar County | 18,430 | 579 | 32 | -0.3% |
| Poweshiek County | 18,313 | 585 | 31 | -1.74% |
| Dickinson County | 18,082 | 381 | 47 | 1.73% |
| Delaware County | 17,746 | 578 | 31 | 1.66% |
| Madison County | 17,391 | 561 | 31 | 4.57% |
| Tama County | 16,788 | 721 | 23 | -1.54% |
| Clayton County | 16,707 | 778 | 21 | -1.88% |
| Iowa County | 16,534 | 586 | 28 | -0.79% |
| Hardin County | 16,450 | 569 | 29 | -2.26% |
| Crawford County | 16,185 | 714 | 23 | -1.83% |
| Clay County | 15,883 | 567 | 28 | -2.8% |
| Jefferson County | 15,177 | 436 | 35 | -3.26% |
| Hamilton County | 14,890 | 577 | 26 | -0.83% |
| Mills County | 14,838 | 437 | 34 | 2.95% |
| Floyd County | 14,721 | 501 | 29 | -5.6% |
| Page County | 14,699 | 535 | 27 | -3.31% |
| Harrison County | 14,652 | 697 | 21 | 0.63% |
| Allamakee County | 14,270 | 639 | 22 | 1.41% |
| O'Brien County | 14,252 | 573 | 25 | 0.68% |
| Kossuth County | 14,176 | 973 | 15 | -4.18% |
| Butler County | 14,005 | 580 | 24 | -2.32% |
| Cass County | 12,915 | 564 | 23 | -1.55% |
| Wright County | 12,754 | 580 | 22 | -1.28% |
| Grundy County | 12,350 | 502 | 25 | 0.11% |
| Lyon County | 12,304 | 588 | 21 | 3.19% |
| Appanoose County | 12,052 | 497 | 24 | -1.88% |
| Union County | 11,734 | 424 | 28 | -3.26% |
| Chickasaw County | 11,602 | 504 | 23 | -3.28% |
| Shelby County | 11,600 | 591 | 20 | -1.01% |
| Cherokee County | 11,216 | 577 | 19 | -3.71% |
| Guthrie County | 10,877 | 591 | 18 | 2.48% |
| Mitchell County | 10,709 | 469 | 23 | 1.11% |
| Hancock County | 10,436 | 571 | 18 | -3.04% |
| Louisa County | 10,268 | 402 | 26 | -5.12% |
| Winnebago County | 10,151 | 400 | 25 | -4.71% |
| Montgomery County | 9,951 | 424 | 23 | -3.71% |
| Keokuk County | 9,790 | 579 | 17 | -2.1% |
| Franklin County | 9,759 | 582 | 17 | -2.32% |
| Clarke County | 9,557 | 431 | 22 | -1.79% |
| Calhoun County | 9,470 | 570 | 17 | -4.3% |
| Sac County | 9,436 | 575 | 16 | -3.63% |
| Howard County | 9,393 | 473 | 20 | -1.06% |
| Humboldt County | 9,313 | 434 | 21 | -2.98% |
| Davis County | 9,284 | 502 | 18 | 1.84% |
| Emmet County | 9,083 | 396 | 23 | -2.76% |
| Palo Alto County | 8,906 | 564 | 16 | -0.93% |
| Lucas County | 8,868 | 431 | 21 | 2.87% |
| Greene County | 8,662 | 570 | 15 | -0.99% |
| Monona County | 8,586 | 694 | 12 | -1.83% |
| Decatur County | 7,635 | 532 | 14 | -1.2% |
| Monroe County | 7,418 | 434 | 17 | -2.39% |
| Worth County | 7,376 | 400 | 18 | -0.82% |
| Adair County | 7,341 | 569 | 13 | -2.09% |
| Van Buren County | 7,075 | 485 | 15 | -2.02% |
| Wayne County | 6,842 | 525 | 13 | 5.15% |
| Ida County | 6,787 | 432 | 16 | -3.31% |
| Pocahontas County | 6,716 | 577 | 12 | -5.01% |
| Fremont County | 6,551 | 511 | 13 | -0.37% |
| Osceola County | 5,952 | 399 | 15 | -4.02% |
| Taylor County | 5,827 | 532 | 11 | -0.6% |
| Audubon County | 5,470 | 443 | 12 | -3.7% |
| Ringgold County | 4,635 | 535 | 8.7 | -0.13% |
| Adams County | 3,634 | 423 | 8.6 | -2.05% |
Sources
- US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
- US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
- American Community Survey (2009 - 2013)
- Census QuickFacts
- Historical Populations of States and Counties (1790 - 1990)